148 EXTRACTION OF POTASH 



by catalytic agents, and this is what has been attempted in the 

 present case. (It will be remembered that the function of a 

 catalyst is to increase the speed of a chemical reaction). Heat 

 and pressure were employed. Platinum sponge was also given 

 a trial. 



Apparatus. — The first experiments were made with an or- 

 dinary Kipp carbon dioxide generator. A continuous stream of 

 gas was passed through a water mixture of the finely ground 

 felspar, heat and agitation being furnished by boiling. These 

 experiments were, of course, carried out under atmospheric 

 pressure only. 



In order to conduct the work at higher pressures a special piece 

 of apparatus was obtained. It was essentially a heavy iron 

 retort consisting of a body of 3'/2" steel piping of '/^"thickness. 

 A piece of pipe 131/2" long was taken and the ends closed by 

 screwing on two heavy caps. A head 3" in diameter was cut out 

 of one cap and into this removable head were screwed a pet-cock 

 and an inlet pipe, both 1/2" • The head was held in place by a 

 heavy clamp, and the inlet which extended to within an inch 

 of the bottom of the retort was connected with the gas supply 

 by means of a 3/^" junction. A hole was tapped in the side 

 of the retort for the pressure gauge. 



The gas and pressure were supplied by a cylinder of liquid 

 carbon dioxide, the pressure was also furnished by superheated 

 steam by the simple expedient of boiling with all valves closed. 



The only other piece of apparatus used was a hand spectro- 

 scope with which qualitative tests were made for potassium. 



Analysis. — A quantity of orthoclase sufficient for the work in 

 hand was procured from the geological laboratory and an analy- 

 sis made of it. The following results were obtained. 



Silica. Si02 65.520% 



Alumina. A1 O3 21.520" 



Potash. K2O 11.860" 



Soda, Na20 1.675" 



' Lime, Ca O 151" 



Magnesia, Mg O 004 " 



100.730% 



